[audiophile noob]

Thanks for the responses guys. I have learned a couple of things as well from an Ebay seller - not earth shattering in any way.
 
1. The -EV stands for tubes that are designed for 5000 hours of operation. Non -EV are rated for 3000 hours.
2. There are 6J1P tubes made in the Soviet Union that are not Voskhods - there was another factory called Novosibirisk that also made them. Don't know if they compare well or poorly with Voskhod.
 
FYI - I am trying to purchase Military grade (OTK), Gold grid, matched pair Voskhods made in the 80s based on recommendations on this forum!
 
Quote:

 

The Russian designation is 6Ж1П-ЕВ.
 
6Zh1P-EV and 6J1P-EV are merely transliterations of that.
 

 

 

[Tribbs]

 
 Here are military grade, gold grid 6J1P / 6Ж1П made in the Novosibirsk factory  
 
http://www.ebay.com/itm/6J1P-GOLD-GRID-EF95-6AK5-NOVOSIBIRSK-MATCHED-PAIR-TUBE-70s-/350511816316

 

[mordy]

Hi A Noob,
 
IMHO I would venture to say most Russian tubes were made for the military, so you don't have to look for them specially.
It seems that only Novosibirsk made tubes with gold alloy grids.
About the EV rating: There is another Russian higher rating called DR, which is rated for 10,000 hours of operation. I have not found any 6J1P tubes with this designation. However, there are other tubes out there in the EF95/6AK5 family that are rated for extra long life (10,000 hours). The Amperex PQ series, the Mullard Millenium series, and possibly the GE 5 Star and Sylvania Gold series, although I am not 100% sure about the last two.
(Saw a post somewhere that Telefunken tubes have a very long life span, but I don't know if it refers to the 5654/6AK5 tubes.)
Don't know how much this matters from a practical point of view, because so far very few of my tubes gave up. If you do a lot of tube rolling chances are that you won't play the tubes for a couple of thousand hours before you try the next one. And the next one....
 
 

 

[audiophile noob]

I was passing along some info I was able to learn (in my effort to give back) - I forgot that you guys were already experts.
 
I have placed an order for the Voskhods. I studiously avoided the Novosibirsk factory - because all I know is you guys said Voskhod!

 

[cassper]

Quote:

 

The Russian designation is 6Ж1П-ЕВ.
 
6Zh1P-EV and 6J1P-EV are merely transliterations of that.
 

Oskari, since you pointed it out I would like to correct one very common mistake in this thread regarding transliterations. The stock tube of LD mkIII is not 6N6Pi. It is 6Н6П = 6H6Pi = 6N6P. So 6N6P Gold grid is merely a version of a stock tube, not rolled tube or an upgrade per se.
 

 

[mordy]

Dear Cassper,
 
Just took a look at the stock driver tube that came with my LD MKIII (bought in May 2010). The designation is 6N6П-И (6N6P-I). "I (Russian: И) - optimized for "pulsed" (i.e. switching) mode of operation."
It appears to me that 6N6P and 6N6P-I are two different variants and not the identical driver tube. It also seems logical that 6N6Pi is another way of writing 6N6P-I and the same tube.
The 6N6P gold grid tube is the same tube as any 6N6P, but the he construction is a little different, and it sounds  better to me with more punch in the bass.
 
 

 

[cassper]

Quote:

Dear Cassper,
 
Just took a look at the stock driver tube that came with my LD MKIII (bought in May 2010). The designation is 6N6П-И (6N6P-I). "I (Russian: И) - optimized for "pulsed" (i.e. switching) mode of operation."
It appears to me that 6N6P and 6N6P-I are two different variants and not the identical driver tube. It also seems logical that 6N6Pi is another way of writing 6N6P-I and the same tube.
The 6N6P gold grid tube is the same tube as any 6N6P, but the he construction is a little different, and it sounds  better to me with more punch in the bass.
 
 

In that case you are absolutely right, 6N6P-I is indeed a different tube. Interesting information, as the Product manual and the web only mention 6N6P. Also, my mkIII, bought roughly a month ago, sports 6N6P (0381) tubes. No surprise that in your case 6N6P improved sound over 6N6P-I as these are, from available info, not very suitable for audio purposes. I have some Sovtek 6N30P-EV on the way to me, and will try also benefits of the 6N6P gold grids (cheap experiment), this is as far as I want to go with the power tubes. 

 

[olemungu]

Mordy,
 
Any difference between the gold Novosibirsk vs Voskhods based on your testing?
 

 

[mordy]

Dear Olemungu,
 
Let's get it straight - I cannot compare the  Novosibirsk and Voskhod gold tubes to each other. Novosibirsk makes the various POWER tubes such as 6N6P and 6N6P-I.
Voskhod makes different variants of the 6Zh1P-EV and 6J1P-EV DRIVER tubes.
All in all, I found that the gold grid tubes, both power and driver tubes, sounded better in my system in comparison to non-gold grid tubes.
 
As to the difference between 6N6P and 6N6P-I I found that the 6N6P sounded better with driver tubes with accented treble, but with other tubes 6N6P-I was better. All in all, my personal preference in power tubes is the the gold grid 6N6P.
 
I would be interested in hearing more about your sources and reasons that the 6N6P-I is not as well suited for audio applications - I have not come across this information myself.
 
It is worthwhile to note that the main differences and improvements in sound come from the driver tubes. The power tubes make a much smaller difference, maybe 15%. However, if they make a treble heavy tube pleasant and listenable, that could mean much more of an improvement to you.

 

[olemungu]

Since some of the sources are reasonably cheap, I will just test it out. Any major side effects of using non matching drivers? Also since some of these are sold in bulk without matching, any ways to match it at home?

 

[Oskari]

 
Quote:

The stock tube of LD mkIII is not 6N6Pi. It is 6Н6П = 6H6Pi = 6N6P.

Quote:

It also seems logical that 6N6Pi is another way of writing 6N6P-I and the same tube.

 
I believe that the "Pi" is a reflection of the fact that the Greek capital letter pi (Π) looks exactly the same as the Cyrillic capital letter pe (П).
 

 

[cassper]

Quote:

 
 
I believe that the "Pi" is a reflection of the fact that the Greek capital letter pi (Π) looks exactly the same as the Cyrillic capital letter pe (П).
 

It is, indeed... In that case, however, we would be talking about 6H6Pi (=6N6P). The tube that Mordy mentioned is 6H6П-И (6H6Pi-И, =6N6P-I). There have been discussions on other forums about suitability of this tube for audio purposes due to its designation for the pulse operation and relatively short operation span (cca 500hrs). On the other hand it is being mentioned that 6N6P-I was later renamed to 6N30P, of which variants are considered to be superior to 6N6P. But again, many people have 6N6P in very high regard and consider 6N30P as a hype not worth the price premium.

 

[mordy]

Did some research the internet about the 6N6P-I tube. This tube was used in intermittent pulse mode in computers. The spec sheet rating is only 500 hours for this tube (compared to the 6N6P which is rated for 3000 hours).
However, the consensus of many posts was that this short life span pertains to very demanding applications in tanks or airplanes, and that this tube should last much longer in audio use.
Another very interesting aspect of manufacturing was that the factories were held to rigid government specs that could not be changed. However, in order to please customers they would change the specs to suit certain applications but not put these changes into writing. A certain customer could be reliably assured of getting the same upgraded quality from the same factory for a certain tube.
Regarding the gold grid tubes one post stated that they do not sound different but that the manufacturing process was more difficult and rigorous, and thus the life expectancy of these tubes should be greater. (Personally, I find a sonic improvement.)
Another interesting post mentioned that the best quality Russian tubes were made in the 60's and 70's. After the fall of communism there was much less demand for vacuum tubes, and manufacturing equipment and raw materials were sold for scrap. (Experienced workers were lost to manufacturing as well.)
A number of posts stated that the highly touted 6H30 tubes made in the 90's and later are inferior to the early 6N6P tubes. (Early ones are very good, though, especially 6N30-DR)
And here is a funny (and hopefully useful) quote:

"OTK

Otbor tiehneecheskovo kachiestva - quality control level - they used the stamp OTK followed by a number. The lower number the better. The zero is if I am not mistaken the best. Zero was strictly military;  one - also military but not for nukes, and so on. I would like to read more about this aspect one day.
Just don't forget that in the Soviet times for producing a faulty tube the worker could face 10 years in Siberian labour camp in minus 50 degrees without gloves. These times were not funny at all."
 
I immediately ran to check my Voskhod gold grid groove tubes. Phew! OTK  1!  OK, so not OTK 0. I settle for no nukes; now I'll be able to sleep well....
Shucks, my 1985 6N6P-I say OTK 5! And my 1978 6N6P say OTK 4! Luckily, both my 1975 gold grid 6N6P and 1975 regular 6N6P tubes don't have the OTK symbols on them - ignorance is bliss. Good night!
 
 

 

[mordy]

Tried to do a little research on the deciphering of the OTK symbol and the various numbers in the rhombus following the OTK letters.
Basically, OTK is a Russian abbreviation for Quality Control. It is a symbol that is used on a number of products, and it is not specific to military use only. Sometimes the OTK letters are followed by a number, i.e. OTK 23. This simply means Quality Control, inspected by inspector 23.
 
The numbers within the rhombus could be 1,3, 5, 7 and 9. The meaning of these numbers is as follows (from a Russian seller on EBay):
[size=10pt]1 - usual OTK
3 - usual + climate test
5 - military
7 - military + climate test
9 - a special series[/size]
 
Some of my Russian tubes have the OTK symbols printed on them and some not. Those that do not have them probably come from bulk packages that have the  OTK symbols  printed on the large box they came packaged in. (So far I have seen the numbers 1, 3 and 5 on my tubes.)
 
My source claims that for audio use the different rhombus numbers do not matter. I would venture to guess that category 5 and 7 may be more rugged, perhaps corresponding to the W (6AK5W) in the US nomenclature, which indicates a more rugged construction for military use.

 

[Tribbs]

That's really cool.  Thanks for posting your findings.